Exposure to a Low Lead Concentration Impairs Contractile Machinery in Rat Cardiac Muscle

Abstract

Lead exposure has been considered to be a risk factor for hypertension and cardiovascular disease. Our purpose was to evaluate the effects of low plasma lead concentration on cardiac contractility in isolated papillary muscles. Wistar rats were divided in control group or group treated with 100 ppm of lead acetate in the drinking water for 15 days. Blood pressure (BP) was measured weekly. At the end of the treatment period, the animals were anesthetized and euthanized, and parameters related to isolated papillary muscle contractility were recorded. The lead concentrations in the blood reached 12.3 ± 2 μg/dL. The BP was increased in the group treated with 100 ppm of lead acetate. Lead treatment did not alter force and time derivatives of the force of left ventricular papillary muscles. In addition, the inotropic response induced by an increase in the extracellular Ca(2+) concentration was reduced in the Pb(2+) group. However, the uptake of Ca(2+) by the sarcoplasmic reticulum and the protein expression of SERCA and phospholamban remained unchanged. Postrest contraction was similar in the both groups, and tetanic peak and plateau tension were reduced in lead group. These results demonstrated that the reduction in the inotropic response to calcium does not appear to be caused by changes in the trans-sarcolemmal calcium flux but suggest that an impairment of the contractile machinery might be taking place. Our results demonstrate that even at a concentration below the limit considered to be safe, lead exerts deleterious effects on the cardiac contractile machinery.

Co-exposure subacute toxicity of silica nanoparticles and lead acetate on cardiovascular system

“…7 Epidemiology studies indicated that exposure to even low levels of Pb was associated with an increased incidence of clinical cardiovascular end points such as hypertension, arteriosclerosis, coronary heart disease, and stroke. 8,9 Pb could deposit abnormally on the arterial wall and heart valve and cause constructional and functional transformation of cardiovascular system. 10 Yet, there is no clear evidence to indicate whether co-exposure to SiNPs and Pb could lead to cardiovascular toxicity in vivo.…”

Lead poisoning: acute exposure of the heart to lead ions promotes changes in cardiac function and Cav1.2 ion channels

“…As such, these channels and transporters are likely targets during lead poisoning. Moreover, there are some clinical reports about heart effects seen during lead poisoning, but there are only a few studies that have attempted to understand the effects of lead exposure in the heart at the molecular level (Basha et al 2012;Bhatnagar 2006;Kurppa et al 1984;Missiaen et al 2000;Scoote and Williams 2004;Silva et al 2015;Taylor 1996;Tollestrup et al 1995;Williams et al 1983). In this paper, we study the effects of Pb 2+ on contractility, heart rate and arrhythmias in isolated heart cells from guinea pigs and mice.…”

Low-level lead exposure and cardiovascular disease: the roles of telomere shortening and lipid disturbance

“…Undoubtedly, these findings possess immediate meaning and significance for public health around the world (Silva et al, 2015). Although environmental and occupational exposure to lead has declined in the past decades in Europe (Pawlas et al, 2013;Hrubá et al, 2012), the risk for damage to cardiovascular functions by short-term or low-concentration lead exposure should not be underestimated.…”

“…Nevertheless, many recent studies found that low levels of lead exposure, even below the threshold considered safe, could bring about potential harm and detrimental effects to cardiovascular systems (Silva et al, 2015;Fiorim et al, 2011), which posed a challenge to the established safe threshold as well as a caution for the world on the ubiquitous low levels of lead exposure. The safe threshold has varied dramatically, constantly going lower and lower over the past.…”

“…Lead is a ubiquitous toxin in the environment and certain professions, and exerts a harmful influence upon all organs and systems of the body, eventuating a wide variety of illnesses. Lead exposure has been considered a risk factor for cardiovascular disease (Kossowska et al, 2013;Zota et al, 2015;Silva et al, 2015) with great awareness. Lead's toxicity has led to its fading out for some uses gradually.…”